474 SEC. 12. APPLIED MECHANICS. 



1980. Model of Dawes' and Holt's Hydraulic Shears. 



In order to avoid buckling or bending either half of plate cut in 

 two, a strip of metal equal to the thickness of the plate is sheared 

 out of the plate, and the gap thus formed is utilised to allow the 

 plate to pass the tie connecting the upper and lower blades ; this 

 machine can thus cut any size of plate. Henry P. Holt, C.E. 



2046. Circular Knitting Machine. (J. A. Tielen's Patent, 

 1842.) Sennet Woodcraft, F.R.S. 



2047. Models of Chinese Agricultural Implements (9), 



small mill, &c. Sennet Woodcraft, F.R.S. 



2048. Model for showing the Curves of Screws. 



Sennet Woodcraft, F.R.S. 



2050. Traction Dynamometer, used for ascertaining the 

 draught of carts, waggons, and all agricultural implements that 

 are drawn by horses. Also, for determining the resistance of 

 roads and streets. Royal Agricultural Society of England. 



The instrument is harnessed just like a horse to the implement it is desired 

 to test, and being itself drawn along by one or more horses it registers the 

 total work done in passing over any given distance, the mean and extreme 

 tractive force, the pressure on the back of the horse, and the lateral pressure 

 in such implements as reaping and mowing machines. First used at Bedford, 

 1874. Designed and made for the society by its consulting engineers, Messrs. 

 Eastons and Anderson. See Journal of the Koyal Agricultural Society of 

 England, No. XX., part 2, page 678. 



2051. Appold Friction Dynamometer, of 100 horse-power, 

 used for measuring the work done by steam engines and other 

 prime movers. Royal Agricultural Society of England. 



The prime mover to be tested is coupled to the main shaft of the dynamo- 

 meter, the friction breaks of which are loaded in proportion to the power it is 

 desired to develop. The instrument registers the number of revolutions made 

 in a given time, and this, together with the known weight on the breaks, fur- 

 nishes the data for calculating the work done by the prime mover. This 

 powerful instrument was constructed by the consulting engineers of the 

 society, Messrs. Eastons and Anderson, for the trial of steam ploughing and 

 traction engines at Wolverharnpton in 1871. 



2O53a. Pneumatic Intercepting Apparatus for sending 

 and receiving message carriers in pneumatic despatch tubes of 

 3 inches diameter, to be worked on the circuit system. 



Messrs. Siemens Brothers. 



2052. Diplograph. Writing machine for the Blind, by 



which writing in relief and ordinary writing are performed at the 

 same time. Ernest Recordon, Geneva. 



2O54. Dr. Thursfield's Patent Writing Frame, for 



enabling the Blind, and persons with defective or failing sight, to 



